Failed apoptosis enhances melanoma cancer cells aggressiveness

Recent evidence shows that partial mitochondrial permeabilization and non-lethal caspase activation occur under certain circumstances, though it remains unclear how failed apoptosis impacts established cancers. Using a cancer cell model to trigger non-lethal caspase activation based on either BH3-only protein expression or chemotherapy treatment, we found that melanoma cancer cells failing to undergo complete apoptosis have a particular transcriptomic signature associated with focal adhesions, transendothelial migration and modifications of actin cytoskeleton. To assess the effects of failed apoptosis, we used a BiFC-based (bi-molecular fluorescence complementation) caspase reporter assay expressed via lentiviral transduction into human melanoma cell lines with different metastatic potentials. We then added a doxycycline-inducible system controlling the expression of the pro-apoptotic truncated BID (tBID) protein, capable of activating BAX and thus inducing rapid MOMP and cell death. Caspase positive (VC3AI+ve/DAPI-ve/AnnexinV-ve) and negative ( VC3AI-ve/DAPI-ve/AnnexinV-ve cells) cells were sorted for gene expression analysis.